Advances in the catheterizations techniques, stent designs, and pharmacotherapeutics have reduced adverse ischemic event rates such as cardiovascular death, ST (stent thrombosis), recurrent myocardial infarctions, and revascularizations in patients with coronary artery disease undergoing elective or acute percutaneous coronary intervention (PCI). However, the same antithrombotic regimens also increase bleeding risk, and a cornerstone of contemporary cardiovascular interventions is balancing ischemic and bleeding events in order to optimize the net benefit for the individual patient.
Bleeding complications in patients undergoing cardiovascular interventions have previously been underappreciated. Over the decade, however, awareness has gradually raised that adverse bleeding outcome after PCI carries substantial hazard comparable to that of post-PCI myocardial infarction associated with mortality. A growing number of studies showing the impact of bleeding on short- and long-term mortality have promoted bleeding end points to a pivotal metric, increasingly applied as a single and combined primary end point in randomized controlled trials (RCTs). The composite end point of net adverse clinical events (NACE), assessing both ischemia and bleeding in the same outcome measure, was conceived to investigate the balanced effect of novel therapeutic agents or clinical strategies in antithrombotic treatment regimens.
However, understanding the full impact of bleeding on outcome is still challenging. While ischemic adverse events are mostly narrowly adjudicated by widely accepted consensus definitions such as ST by the academic research consortium or myocardial infarction (MI) by the global definition of MI, bleeding assessment has been based on a large and very heterogeneous palette of definitions, often arbitrarily modeled as per-protocol criteria for specific clinical trials.
In the following, we will summarize the existing bleeding risk scores, their comparability, and their effect on clinical outcomes, as well as highlight their importance in contemporary clinical decision making and clinical trial design.
BLEEDING EPIDEMIOLOGY IN INTERVENTIONAL CARDIOLOGY
Bleeding is the most common noncardiac complication after PCI and leads to incremental increase in costs of health care. Rao et al1 recently published an updated bleeding model based on the US National Cardiovascular Data Registry (NCDR) in order to predict the risk of postprocedure major bleeding complications among patients undergoing PCI. Bleeding was defined as adverse events occurring within 72 hours after PCI or before hospital discharge, and the criteria are described in Table 59-1. In contemporary clinical practice describing more than 1 million procedures from over 1000 invasive US centers, this report identified over 60,000 PCI procedures, with postprocedure bleeding comprising an incidence of 5.8% in this cohort. Among the bleeding events, 32% related to a specific anatomic location; 44.6% were detected due to a pre- to postprocedure hemoglobin decrease, 21.8% by a blood transfusion, and 1% by cardiac tamponade; and 0.6% were intracranial hemorrhage events.1 Approximately half of bleeding events occur at the arterial site and may cover a large spectrum of clinical importance from uncomplicated subcutaneous access site hematoma to fatal retroperitoneal bleeding.